Unsaturated lower aliphatic acids and esters, and particularly methacrylic acid and its esters, are used in the preparation of polymers which find wide commercial applicability.
The preparation of such unsaturated lower aliphatic acids and esters is typically carried out by the catalytic oxidative dehydrogenation of the corresponding saturated acids and esters. A wide variety of catalysts has been proposed for such reactions. However, the catalysts previously proposed share one or more deficiencies. Earlier catalysts, for example, frequently result in an undesirably low conversion in the catalytic process or low selectivity for the desired unsaturated acid product. Others exhibit short catalytic life or higher cost than would be commercially acceptable. Accordingly, continued effort has been directed toward the development of better catalysts for this oxidative dehydrogenation reaction.